The transfer or pumping up of solids such as fish in water as a transfer medium as shown in FIG. 1, a range of lift more than 10 m on the suction side is theoretically impossible. In practice, disadvantageously, it is impossible for a pump to have a range of lift as high as 10 m, and water can be forced to a maximum height of 7 or 8 m by a pump. Further, even with a lift range of less than 5 m, transfer power is lowered if the whole length of the suction pipe is large.
In using a pump adapted to accelerate a liquid flow by an impeller, a high range of lift on the suction side lowers the transfer power of the pump and further damages the solids to be transferred. Namely, if the range of lift on the suction side is high, suction force has to be increased, for example, by the speed up of the rotation of the impeller. But with such a high speed rotation of the impeller, the solids passing through the pump are subjected to a violent force by the impeller and are apt to be damaged.
If a transfer apparatus damages the solids to be transferred, the use of the apparatus is remarkably limited.
Such solids transfer apparatus is used to transport fish, sometimes live fish and the like. Consequently, the apparatus must not impart great shock to fish to be transferred at any stage of the operation. A great shock imparted to the fish transferred by a pump lowers the quality of the fish or kills the same.